Command Filter Adaptive Asymptotic Tracking of Uncertain Nonlinear Systems With Time-Varying Parameters and Disturbances

• Published in: IEEE transactions on automatic control Vol. 67; no. 6; pp. 2973 - 2980
• Main Author: Li, Yuan-Xin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive control; Asymptotic properties; asymptotic tracking control; Backstepping; Closed loop systems; command filter backstepping; Control systems design; Controllers; Convergence; Disturbances; Feedback control; Liapunov functions; Lower bounds; Nonlinear systems; Parameter uncertainty; Target tracking; Time-varying systems; Tracking control; uncertain nonlinear systems; unknown virtual control coefficients
• ISSN: 0018-9286; 1558-2523
• DOI: 10.1109/TAC.2021.3089626

This article is devoted to the adaptive asymptotic tracking for a class of uncertain nonlinear systems. The presence of unknown time-varying parameters and uncertain disturbances makes the systems in question essentially different from those in the related works. By skillfully combining adaptive technique and command filter-based backstepping, a novel command filter adaptive tracking controller is successfully designed to achieve asymptotic tracking. The typical feature of the proposed controller lies in the introduction of a smooth function with positive integrable time-varying function, which makes the controller powerful enough to compensate the unknown time-varying parameters and uncertain disturbances. Remarkably, a novel Lyapunov function by incorporating the lower bounds of control gains is used to prove the stability of the closed-loop system. Compared with some existing command filter-based backstepping, the conditions on the virtual control coefficients and disturbances are relaxed. Finally, the effectiveness of the proposed method is shown by a simulation example.